This domain is found at the C-terminus of some MerR family transcription factors. The domain has an alpha-helical globin-like fold [1]. The family includes Mta a central regulator of multidrug resistance in Bacillus subtilis.

1: Structural basis for antibiotic recognition by the TipA class of multidrug-resistance transcriptional regulators. Kahmann JD, Sass HJ, Allan MG, Seto H, Thompson CJ, Grzesiek S; EMBO J 2003;22:1824-1834. PMID:12682015